<L 


JULY,  1875. 


No.  t7. 


BULLETIN 


OF  THE 


UNIVERSITY  of  CALIFORNIA 


THESIS 

ON  UTILITY  AND  METHODS  OP  SOIL  ANALYSIS. 
BY  L.  S.  BURCHAED, 

Candidate  for  the  Degree  of  Bachelor  of  Philosophy. 


It  is  the  object  of  Agriculture  to  supply  to  the  world  the 
crude  materials  of  what  we  eat  and  wear  ; or,  as  more  common- 
ly known,  Agriculture  is  the  art  which  pertains  to  the  cultiva- 
tion of  the  soil,  and  to  the  rearing,  feeding,  and  management 
of  live  stock.  There  is  no  art  more  important  than  Agricul- 
ture, nor  noite  which  presents  so  many  subjects  of  scientific 
inquiry- and  vital  interest.  And  yet,  but  few  subjects  of  simi- 
lar moment,  but  what  have  received  far  more  thorough  and 
scientific  research.  I fancy  this  is  because  agricultural  science 
is  as  yet  in  its  infancy.  Other  sciences  must  first  be  developed 
before  this  could  make  any  satisfactory  advancement: — Chem- 
istry to  give  methods  of  analysis,  and  Geology  to  tell  of  soil 
formation.  Botany  and  Zoology  must  also  make  their  contri- 
butions, while  years  of  experience,  and  practical  testing  of  the- 
ories should  add  their  corroboratory  testimony. 

Agriculture  takes  rank  among  the  highest  sciences,  but  sin- 
ularly  enough,  is  but  lightly  appreciated,  even  by  the  class  of 
’i  who  should  give  it  the  most  attention.  The  farmers,  as  a 
s,  are  not  sufficiently  informed,  and  among  most  of  the  edi- 
ted, other  subjects  are  given  greater  prominence,  while 
riculture  receives  only  a casual  consideration.  The  decay 
old  empires,  and  the  decline  in  national  vigor  of  the  people 
f those  governments,  clearly  indicate  that  the  farmer  must 
y 139 


University  Press,  Berkeley 


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BULLETIN  OF  THE 


have  regard  to  the  manner  in  which  he  treats  the  soil  from 
whence  comes  his  bread;  while  the  statesman  should  not  be 
ignoranf  of  one  of  the  grandest  elements  of  national  prosperity, 
viz : soil  fertility. 

The  farmers  of  every  age  and  country  have  first  planted  one 
crop  after  another,  without  any  regard  for  the  soil’s  treatment. 
And  quite  naturally  enough,  for  they  did  not  know  what  com- 
posed the  soil  or  the  plants  growing  upon  it.  They  did  not 
know  how  to  care  for  their  land,  and  consequently  it  soon  be- 
gan to  exhibit  signs  of  infertility.  The  difficulties  they  could 
not  remedy,  but  other  countries  were  fertile  and  to  them  many 
of  the  people  emigrated.  Men,  however,  cannot  easily  migrate, 
nor  are  such  migrations  conducive  to  national  prosperity;  hence 
the  leading  men  of  the  nation,  perceiving  the  evil,  began  to 
give  attention  to  the  soil’s  cultivation.  Among  the  Hebrews 
the  land  had  its  periods  of  rest.  Other  and  later  generations 
thought  of  adding  something  to  the  soil.  But  what  should  be 
added,  and  should  the  same  fertilizer  be  added  to  all  soils? 

China  and  Japan  solved  the  problem  quite  satisfactorily  for 
themselves.  But  they  shut  themselves  up  from  the  rest  of 
mankind,  and  we  Indo-Europeans  remained  in  ignorance  as 
the  rolling  centuries  passed  along. 

A host  of  fertilizers  have  been  tried  and  many  of  them  found 
to  improve  the  soil’s  fertility.  But  as  the  same  fertilizer  would 
not  answer  on  different  soils,  it  was  with  much  reason  presum- 
ed, that  a chemical  analysis  of  the  soil  and  of  its  vegetation, 
and  of  the  substances  to  be  added  would  give  all  the  required 
information  for  maintaining  the  soil’s  productiveness. 

If  we  knew  what  to  add  to  the  soil,  there  seemed  to  be  no 
question,  but  that  the  soil  which  yielded  one  bale  of  cotton  to 
the  acre,  and  which  now  yields  but  one-fourth  of  a bale,  would 
yield,  by  this  new  and  really  marked  advance  in  agricultural 
knowledge,  from  two  to  three  bales  per  acre.  Our  expecta- 
tions were  high,  but  our  two  or  three  bales  of  cotton  to  the  acre 
were  rarely  realized.  What  was  the  difficulty?  We  certainly 
are  in  possession  of  an  important  factor  in  crop  culture. 

Not  every  analysis  was  correct,  and  no  thought  was  tak 
as  to  whether  the  important  soil  constituents  were  in  an  a" 
able  or  unavailable  condition.  A mechanical  analysis  mus^ 
made  in  addition  to  the  chemical.  The  physical  properties 
the  soil,  whether  open,  light,  porous,  heavy,  dark,  deep,  or  sin 
low;  its  dryness,  warmth,  division;  whether  in  a rainy  or  rai. 

140 


UNIVERSITY  OF  CALIFORNIA. 


3 


less  region;  climate,  high  or  low  land;  kinds  of  crops  raised 
on  the  soils;  how  long  under  cultivation;  drainage,  etc.;  all 
these  factors,  and  more,  are  to  he  taken  into  consideration. 
Hence  a single  chemical  analysis,  while  giving  valuable  infor- 
mation to  the  agriculturist,  is  only  one  of  .many  things  which 
determine  the  value  of  the  soil  and  its  adaptation  to  particular 
crops. 

This  fact,  however,  is  generally  lost  sight  of ; many  giving 
undue  prominence  to  the  soil’s  chemical  analysis,  while  others, 
among  the  number  Professor  Johnson,  consider  it  as  compara-r 
tively  useless,  and  urge  such  objections  as  the  following:  Two 
soils  may  be  of  quite  similar  composition,  and  yet  be  very  un- 
like in  fertility.  The  least  productive  one,  is  so  because  of 
some  physical  condition:  as  a want  of  under-drainage,  lack  of 
rain,  depth  of  soil,  etc. 

To  correct  the  soil’s  physical  defects  often  improves  at  once 
its  chemical  condition.  A correct  chemical  analysis  of  the  soil 
requires  much  time  and  is  expensive;  and  when  made,  one  is 
not  able  to  tell  whether  his  soil  is  just  now  fertile  or  barren. 
Some  soils,  naturally  sterile,  by  adding  four  hundred  pounds 
of  guano  to  the  acre,  manifest  a wonderful  productiveness. 
The  analysis  represents  but  a small  part  of  the  field,  and  does 
not  indicate  the  soil’s  openness,  heaviness,  etc.  Johnson  sug- 
gests, instead  of  chemical  analysis,  experiments  on  different 
plots  of  land  with  those  fertilizers  most  likely  to  cause  the  par- 
ticular soil  to  become  fertile.  These  are  strong  objections 
against  the  chemical  analyses  of  soils,  if  such  analyses  were 
one’s  only  source  of  information  respecting  the  soil’s  composi- 
tion, condition,  and  value.  But,  when  we  know  that  chemical 
analysis  is  only  one  factor  of  our  knowledge  of  the  soil  and  its 
intelligent  cultivation,  the  above  objections  appear  a little 
specious,  and  thus  lose  most  of  their  force.  Is  it  not  rational 
to  suppose  that  a soil  rich  in  certain  ingredients  would  be  bet- 
ter adapted  to  a particular  class  of  plants  demanding  those  par- 
ticular ingredients,  than  it  would  be  for  any  other  class  of 
plants  ? To  determine  by  experiment  alone  what  a soil  is  good 
for,  is,  to  say  the  least,  a lengthy,  tedious,  and  costly  process. 
In  the  case  of  *•  poison  soils,”  which  to  all  appearances  are  fer- 
tile, and  yet  contain  substances  which  are  injurious  to  crops, 
experiment  is  almost  folly.  Take  this  example:  some  soil  of 
Bae’s  Island,  Beaufort  county,  South  Carolina,  appeared  to  be 
good  soil,  but  would  not  grow  cotton.  The  planters  did  not 

145 


4 


BULLETIN  OF  THE 


know  how  to  obviate  the  difficulty.  They  had  tried  Professor 
Johnson’s  blind  experiments  to  their  entire  satisfaction.  The 
soil  was  analyzed,  and  found  to  contain  some  proto-sulphate  of 
iron,  a substance  which  is  poisonous  to  plants.  The  chemist 
gave  the  remedy  also,  viz:  under-drainage,  aeration,  and  the 
addition  of  some  lime. 

Comparative  Chemical  Analysis  of  Soils  not  only  tells  one 
what  is  the  soil’s  composition,  but  also  the  ratio  of  its  plant  in- 
gredients to  each  other  and  to  those  found  in  other  soils. 

If  a soil  is  found  to  be  rich  in  the  nutritive  plant  ingredients, 
viz:  K"Q,  P205,  CaO,  N and  C,  we  know  what  crops  would,  in  all 
probability,  grow  most  successfully  upon  it;  and  if  deficient  in 
any  one  of  these  elements  of  plant  foods,  what  particular  fer- 
tilizer could  be  most  advantageously  applied.  For  example : 
in  a soil  containing  a small  proportion  of  lime  and  sulphuric 
acid,  let  leguminous  plants  as  peas,  beans,  etc.,  be  planted;  this 
soil  would  soon  give  out;  but,  by  the  addition  of  an  occasional 
coat  of  gypsum,  its  fertility  is  maintained.  Again,  if  in  a soil, 
which  is  poor  in  phosphates,  cereals  are  planted,  we  know  it 
will  soon  become  exhausted,  and  that  our  remedy  is  to  add  to 
the  soil  super-phosphates. 

These  remedies  are  not  infallible  ones  by  any  means,  and  the 
soil  which  is  rich  in  K20,  CaO,  P205,  N.  and  C.,  may  have  these 
compounds  in  an  unavailable  form;  but  we  have  much  light 
thrown  upon  the  soil’s  permanent  value,  and  probable  adapta- 
tion. A soil  which  is  rich  in  this  plant  food,  will  undoubtedly 
contain  much  of  it  in  an  available  form. 

By  the  Mechanical  Analysis,  and  the  observations  and  in- 
quiries made  in  connection  with  it,  we  obtain  very  much  addi- 
tional knowledge  of  the  soils  condition  and  value.  A soil  com- 
posed mostly  of  fine  silicious  silts,  and  a small  per  centage  of 
clay,  we  know  is  very  heavy,  will  clog  to  the  plough,  and  cakes 
when  drying.  Coarse  ingredients  make  the  soil  more  porous 
and  light.  We  find  that  the  clay  in  the  soils  is  the  richest  in 
mineral  ingredients,  holds  the  most  moisture,  ammonia  and 
other  soluble  salts,  and  its  insoluble  residue  is  comparatively 
small.  A soil  of  coarse  sand  is  infertile,  subject  to  drought, 
and  will  not  allow  plant  food  to  accumulate.  A soil  of  fine 
sand  with  some  clay  is  a good  one,  especially  if  derived  frorft  eas- 
ily decomposed  rocks. 

Thus  we  find,  that  a chemical  and  physical  analysis  of  the 
soils  lies  at  the  foundation  of  a proper  estimate  of  its  capacity, 

142 


UNIVERSITY  OF  CALIFORNIA. 


5 


adaptation,  and  future  value.  The  soil  contains  the  ances- 
tral remains  vof  past  ages,  and  is  the  great  store-house  from 
which  we  draw  most  of  life’s  supplies;  consequently,  a scientific 
inquiry  into  its  composition  and  value,  is  a matter  of  prime  im- 
portance: not  alone  to  the  farmer,  but  to  the  statesman  also. 
Such  an  inquiry  tells  us  what  is  in  the  soil,  in  what  condition, 
the  physical  structure  of  the  soil,  what  crops  are  best  to  plant, 
and  what  fertilizers  to  add.  Let  us-  now  consider  the  methods 
of  conducting  this  inquiry. 

SELECTING  SPECIMENS. 

Before  commencing  the  analysis,  and  at  the  place  of  gather- 
ing the  soil,  it  is  necessary  to  make  note  of  a few  important  par- 
ticulars. 1st.  As  to  the  locality;  whether  hillside  or  valley 
land,  how  near  to  mountains — in  a word,  something  of  the  top- 
ography of  that  section.  2d.  Underlying  geological  formation, 
as  well  as  that  from  which  the  soil  has  been  derived.  3d.  Depth 
of  soil,  surface,  and  the  obvious  physical  characteristics  of  the 
soil.  4th.  Local  vegetation,  natural  and  cultivated;  how  long 
under  cultivation,  and  what  crops  grown;  whether  manured, 
and  what  manures  used;  color  of  soil  taken;  average  rainfall;, 
and  any  other  points  of  special  importance  pertaining  to  that 
particular  locality.  To  the  above  information  is  added  the 
farmer’s  experience  in  cultivation  of  that  particular  soil. 

Sub-soil  is  preferably  taken  for  analysis,  because  in  surface 
soils  the  organic  ingredients  materially  interfere  with  the  opera- 
tion of  the  analysis, as  well  as  with  the  interpretation  of  its  results. 
The  investigation  of  sub-soils  is  better  calculated  to  furnish 
reliable  indications  of  the  agricultural  peculiarities  of  extended 
regions  than  that  of  surface  soils,  which  are  more  liable  to  local  va- 
riations, and  usually  differ  from  the  corresponding  subsoils,  in 
about  the  same  general  points.  The  surface  soil  generally  has 
the  largest  amount  of  immediately  available  plant  ingredients, 
while  the  sub-soil  has  the  largest  supplies  for  future  use. 
The  following  table  from  Prof.  Hilgard’s  Keport  on  the  Agri- 
culture of  Mississippi,  further  illustrates  their  chemical  differ- 
ence. 


143 


6 


BULLETIN  OF  THE 


Analysis  of  Upland  Soil  and  Sub-soil  from  Claiborne  County , 

Mississippi. 


Surface  soil. 
Sub-soil .... 

Insolu. 

part. 

87.6 

79.5 

K20. 

.458 

.741 

Na20. 

.124 

.248 

CaO. 

.244 

.238 

MgO. 

.545 

.830' 

Mn304. 

.205 

.346 

Surface  soil . 
Sub-soil .... 

Fe203. 

3.231 

5.634 

A1203. 

4.84 

8.849 

PA. 

.105 

.092 

so3. 

.028 

trace. 

Volatile 

matter. 

3.073 

3.476 

The  specimen  for  analysis  should,  whenever  possible,  be  'of 
virgin  soil,  taken  from  some  one  or  several  spots,  carefully  se- 
lected as  correctly  representing  the  average  character,  undis- 
turbed by  local  accidents,  such  as  cultivation,  roads,  gullies, 
cattle,  etc.  Make  vertical  cuts  showing  distinctly  the  depth  of 
surface  soil  and  sub-soil,  and  of  each  take  a specimen  of  at 
least  10  pounds,  after  thoroughly  breaking  the  clods  and  mix- 
ing, with  a spade,  on  a cloth  spread  on  the  ground,  the  pile 
thrown  out  of  each — the  larger  the  better.  A pound  or  two  of 
the  specimen  is  then  air-dried,  carefully  triturated  in  a porcelain 
mortar  with  a wooden  pestle,  and  sifted  through  a sieve 
whose  meshes  are  .8mm  (=.03)  diameter.  We  now  have 
the  dry  “ fine  earth  from  this  point  the  two  analyses 
branch. 

MECHANICAL  ANALYSIS. 

We  shall  first  take  up  the  mechanical  or  silt  anal- 
ysis. Take  15-20  grammes  of  the  steam-dried  “fine  earth” 
and  boil  for  twenty-four  to  thirty  hours  in  distilled  water. 
This  is  done  to  completely  disintegrate  the  soil  particles. 
The  second  process  is  to  separate  the  clay  from  the  silt 
and  sand,  as  the  presence  of  clay  in  the  elutriator  would  ma- 
terially interfere  with  the  proper  separation  of  the  sediments. 
The  clay  is  thus  separated : thoroughly  stir  the  boiled  liquid  and 
sediments  in  a quantity  of  distilled  water,  and  allow  to  settle 
for  such  a length  of  time  as  will  allow  sediments  of  .25mm  hy- 
draulic value  to  subside;  the  process  is  repeated  with  smaller 
quantities  of  fresh  water  until  no  sensible  turbidity  remains 
after  allowing  due  time  for  subsidence.  As  some  fine  silt  sedi- 
ment is  poured  out  with  the  clay  water,  and  this  separation  must 
be  repeated,  unite  the  clay  waters (4-8  litres),  stir  them  up,  allow 
to  settle  for  eight  minutes  if  the  liquid  stands  at  the  height  of 

144 


UNIVERSITY  OF  CALIFORNIA. 


7 


200mm  and  then  pour  off  the  clay  water.  The  sediments  are  now 
ready  for  the  elntriator.  The  clay  water,  however,  still  contains 
silt  of  <0.25mm  h.  v.  which  is  separated  by  putting  the  clay  water 
in  a cylindrical  vessel  to  the  height  of  200mm  , allowing  to  sub- 
side for  twenty-four  hours,  then  decanting  the  clay  water  and 
kneading  the  silt  with  a rubber  pestle.  Fresh  distilled  water 
is  again  added,  the  whole  agitated  and  allowed  to  subside  for 
another  twenty-four  hours.  Kepeat  the  operation  until  the 
decanted  liquid  is  clear,  or  fails  to  become  so  by  the  addition 
of  salt  water. 

The  clay  is  precipitated  from  the  clay  water  by  adding  50  c.  c. 
of  saturated  brine  to  each  litre  of  clay  water. 

Collect  the  precipitate  on  a weighed  filter,  wash  with  weak 
brine,  dry  at  100°C  and  weigh.  The  salt  in  the  clay  is  then  washed 
out  with  (NH4)2C1,  and  the  weight  of  the  salt  in  the  filtrate  is 
determined  by  Evaporation,  ignition  and  weighing.  Knowing 
this  weight  we  can  easily  determine  that  of  the  clay.  The 
amount  of  clay  in  the  purest  natural  clays  rarely  reaches  75 
per  cent;  40 — 47  in  the  heaviest  clay  soils,  and  10 — 20  in 
ordinary  loams. 

Separation  of  the  silt  and  sand  sediments . 

These  sediments  are  transferred  to  the  Elutriator,  a cylindri- 
cal vessel  through  which  water  is  made  to  pass,  carrying  along 
with  it  sediments  corresponding'  to  the  different  velocities  of 
water  passing  through  the  tube. 

The  different  velocities  of  the  water  are  determined  by  means 
of  the  graduated  arc  along  which  the  long  arm  of  the  stop-cock 
moves. 

The  cylindrical  vessel  and  churner  at  its  base  are  designed  to 
prevent  the  aggregation  of  flocculent  masses  of  sediment  which 
tend  to  form  in  the  ascending  current. 

Several  other  devices  intended  to  accomplish  the  same  result 
have  been  resorted  to  by  different  persons,  as  Nobel’s  appara- 
tus with  its  four  vessels  of  ever  varying  capacity,  slope  of  sides 
and  variable  head  of  pressure.  This  apparatus  gives  five  differ- 
ent sediments  of  a character  not  approaching  uniformity.  In 
the  same  instrument  with  the  same  kind  of  soil,  one  gets  widely 
different  results. 

Yet  this  apparatus  is  the  one  recommended  by  Caldwell  in 
his  work  on  Agricultural  Chemistry,  and  the  one  used  by  Emil 
Wolff  of  Germany. 


141 


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BULLETIN  OF  THE 


Schultze’s  apparatus  as  modified  by  Fresenius,  is  a tall,  con- 
ical champagne  glass  with  an  adjustable  stream  of  water  de- 
scending through  a tube  in  the  axis.  This  apparatus  is  better 
than  Nobel’s  but  has  the  defect  that  heavy  sediments  collect 
around  the  mouth  of  the  tube,  thus  affecting  the  velocity  of  the 
stream,  and  allowing  a portion  of  the  fine  sediments  to  escape 
the  elutriating  action.  Dietrich’s  apparatus  is  a device  for  car- 
rying the  sediments  in  a stream  of  water,  under  constant  pres- 
sure, flowing  through  four  tubes  of  different  sizes  and  inclined 
at  different  angles.  This  apparatus  will  not  give  like  results 
with  similar  soils.  The  later  and  more  improved  methods  of 
Mueller  and  Schoene  give  more  satisfactory  results  but  have 
the  same  defect  in  common  with  all  the  others;  viz:  no  agita- 
tion of  the  sediments  by  outside  power.  Prof.  Hilgard  uses  a 
Mariotte  bottle  (10  gal.)  to  get  a constant  pressure  for  the  dif- 
ferent velocities  of  water;  a cylindrical  vessel  through  which 
the  sediments  are  borne;  and  a rotary  churn  by  which  the  sedi- 
ments are  constantly  agitated. 

From  this  digression  in  regard  to  the  various  methods  em- 
ployed in  making  silt  analyses,  we  come  back  to  our  mixed  sed- 
iments. These  are  cautiously  put  into  the  elutriator,  and  the 
current  adjusted  to  the  lowest  velocity  to  be  used;  the  flow  con- 
tinuing until  all  sediment  of  that  hydraulic  value  has  passed  off, 
when  the  higher  velocities  are  successively  turned  on. 

Decant  and  filter  the  water  from  the  respective  sediments, 
except  those  below  .25awa-,  which  after  subsiding  to  25 — 
50  c.  c.  m.  are  evaporated  in  a platinum  crucible.  The  sedi- 
ments are  dried  at  100°C  and  weighed. 

Character  of  the  Sediments. 

As  a standard  of  size  measurement  we  take  the  round 
quartz  grain  of  tFo  m.  m.  diameter.  None  of  the  sediments 
are  entirely  free  from  particles  of  the  one  next  below,  owing 
both  to  the  progressive  disintegration  of  conglomerated  parti- 
cles by  the  stirrer,  and  to  the  inevitable  formation  of  the  floc- 
culent  aggregates  of  the  finer  sediments. 

By  measuring  the  sediments  and  comparing  them  with  our 
standard  we  have  the  following; 


146 


UNIVERSITY  OF  CALIFORNIA. 


9 


Table  of  diameters  and  hydraulic  values  of  the  different  Sediments. 


Name.  Diameters.  Velocity  per  second  or 

Hydraulic  value. 


1,  Coarse  Grits . . 1 

— 3 

mm. 

? 

2,  Finer  Grits. . . .5 

— 1 

do. 

? 

3,  Coarse  Sand.  .80 

-90(rb) 

do. 

64 

mm. 

4,  Medium  Sand. 50 

—55  “ 

do. 

32 

do. 

5,  Fine  Sand.  . . .25 

—30  “ 

do. 

16 

do. 

6,  Finest  Sand . . 20 

—22  “ 

do. 

8 

do. 

7,  Dust  Sand. . . .12 

—14  “ 

do. 

4 

do. 

8,  Coarsest  Silt . . 9 

— 9 " 

do. 

2 

do. 

9,  Coarse  Silt. . . 6 

— 7 “ 

do. 

1 

do. 

10,  Medium  Silt.  . 4 

— 5 “ 

do. 

.5 

do. 

11,  Fine  Silt 2.5—  3 “ 

do. 

.25 

do. 

12,  Finest  Silt 

1—  2 “ 

do. 

<.25 

do. 

13,  Clay 

? 

<.0023 

do. 

Strictly  speaking,  none  of  the  sediments  actually  correspond 
to  the  velocities  calculated  from  the  cross  section  of  the  tube 
and  the  water  delivered  in  a given  time,  but  to  higher  ones. 
Still  these  sediments  show  at  once  even  to  the  naked  eye,  that 
the  assorting  process  has  been  quite  successful,  and  that  the 
prominent  characteristics  of  soils  in  these  respects  may  thus  lie 
determined  and  exhibited  to  the  eye  with  a very  satisfactory 
degree  of  accuracy. 

I here  recall  to  mind  the  object  of  silt  analysis:  It  is  to 
convey  to  any  intelligent  mind,  anywhere  in  the  world  a defin- 
ite idea  of  the  agricultural  qualities  of  the  soil;  of  its  tillability, 
perviousness,  and  behaviour  in  wet  and  dry  seasons;  its  liability 
to  washing  etc. ; which  will  be  accomplished  as  soon  as  all  the 
physical  coefficients  belonging  to  each  of  these  sediments  shall 
be  understood. 

CHEMICAL  ANALYSIS. 

Our  attention  shall  now  be  directed  to  the  chemical  analysis. 
In  this  part  of  my  analysis,  as  in  the  mechanical,  I have 
followed  the  method  employed  by  Prof.  Hilgard: 

First:  To  determine  the  Hygroscopic  Moisture  of  the  soil,  a 
quantity  of  the  fine  dry  earth  is  exposed  in  a thin  layer  to  a 
saturated  atmosphere  for  twelve  hours;  weigh  and  dry  at  200°C. 
and  weigh  again.  The  difference  in  weight  gives  the  percent- 
age of  hygroscopic  moisture.  The  object  of  this  determin- 
ation is  to  ascertain  the  soil’s  power  to  resist  drought. 

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BULLETIN  OF  THE 


For  the  general  analysis,  take  2 to  2.5  grammes  of 
the  dry  soil,  and  digest  in  HC1  of  strength  1.115  over 
a water  bath  for  five  days;  evaporate,  moisten  with  HC1, 
redissolve  in  distilled  water,  and  filter.  The  filtrate  con- 
tains the  substances  for  which  we  are  looking,  viz:  K20,  Na20, 
CaO,  MgO,  Fe203  A1203  and  S03.  The  author  of  an  article  in 
the  New  American  Cyclopedia  and  Dr.  McMurtrie  in  Agricul- 
tural report  for  1873  (also  Mr.  Grandeau)  object  to  the  use  of 
HC1  to  dissolve  out  the  available  plant  ingredients,  saying  that 
we  go  farther  than  the  forces  of  nature.  They  would  digest  the 
soil  with  (NH4)2C03. 

NH4  and  C02  act  to  set  free  the  alkalies  in  soils.  Lime 
has  a similar  property.  In  the  soil  we  find  humic,  ulmic, 
crenic,  apocrenic,  sulphuric,  and  oxalic  acids.  Different  plants 
have  different  acids  to  exert  their  solvent  action  on  the  soil  in- 
gredients. So  one  finds  that  (NH4)2C03  is  only  one  of  several 
soil  solvents — a strong  one  to  be  sure,  yet  it  does  not  give  us  in 
solution  all  the  available  plant  ingredients  of  the  soil. 
HC1  does,  being  the  best  single  acid  for  dissolving  inorganic 
substances.  Should  one  get  much  more  of  the  plant  ingredi- 
ents by  using  HC1  than  is  at  once  available  to  the  plant,  he  is 
sajp,  at  least  for  comparative  analyses,  and  also  knows  what  may 
be  useful  in  future  to  the  plant. 

So  far  as  we  know  at  this  time,  no  one  solvent  is  adequate  to 
make  the  distinction  between  available  and  unavailable  soil  in- 
gredients for  all  crops.  The  comparison  of  soils  of  similar  ori- 
gin, analyzed  in  a similar  manner,  is  the  best  we  can  do  at  pre- 
sent. When  we  thus  ascertain  that  a soil  is  rich  in  nutritive 
ingredients,  we  know  that  for  durability,  it  is  preferable  to  oth- 
ers of  its  kind  containing  a smaller  proportion  of  the  same  in- 
gredients. 

In  the  insoluble  residue  the  soluble  silica  is  determined  by 
boiling  in  Na2C03.  The  Fe203  and  A1203  are  precipitated  accord- 
ing to  Rose’s  method  of  boiling  with  (NH4)HO  and  (NH4)  Cl. 
The  mixed  precipitate  is  treated  with  KHO.  Precitatethe  CaO 
by  (NH4)204  and  destroy  the  ammoniacal  salts  by  Lawrence 
Smith’s  method  with  aqua  regia : and  the  residue  is  converted 
into  nitrates,  from  which  S03  is  precipitated  by  Ba(N03)2  The 
alkalies  are  then  separated  by  treatment  with  oxalic  acid;  ignite, 
dissolve  in  water  and  filter.  In  the  residue,  Ba,  Mn,  and  Mg 
are  separated  as  usual.  The  alkaline  carbonates  are  converted 
into  chlorides  and  K precipitated  by  PtCl4;  evaporate  and  dis- 

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solve  the  Na2  salt  by  the  alcohol-ether  mixture,  filter,  ignite,  and 
weigh.  The  Na20  is  determined  by  difference. 

Phosphoric  acid  determination . 

Take  3 to  3.5  grms.  of  dry  fine  earth,  ignite  and  digest  for  five 
days  in  HN03  over  a water  bath,  evaporate  to  dryness,  moisten 
with  HN03,  add  water  and  filter;  precipitate  by  ammonium  mol- 
ybdate, filter  and  dissolve  by  (NH  4 )HO ; reprecipitate  by  MgSO  4 , 
dry,  ignite  and  weigh  as  Mg2P207  ,from  which  the  P205  is  easily 
calculated. 

The  usual  mineral  ingredients  in  the  soil  are,  K,  Na,  Ca, 
Mg,  Mn,  Fe,  A1  and  Si,  as  metallic  elements;  and  P,  F,  C,  S, 
and  Cl  as  non-me tallies.  Preeminently  the  most  important  of 
these,  and  the  ones  requiring  replacement  in  future  by  fertilizers, 
are  K20,  CaO,  P205,N  and  C. 

The  phosphates  are  found  chiefly  in  the  seeds,  especially  of 
cereals;  while  root  crops  draw  more  upon  the  K20  of  the  soil, 
and  leguminous  plants  draw  largely  upon  N,  and  the  phos- 
phates. CaO  and  MgO  are  preeminently  stem  ingredients.  Na, 
Si,  Mn,  Mg,  Fe,  S,  and  Cl  are  generally  found  in  sufficient  quan- 
tities, and  need  no  replacement.  N and  C are  contained  in  hu- 
mus,which  may  be  supplied  by  green-manuring.  Ca,  by  adding 
lime,  which  <also  sets  free  unavailable  K20  and  other  alkaiies. 
P205  is  supplied,  when  needed,  by  bone  phosphates. 

The  grand  law  of  soil  preservation  is  to  return  to  the  soil  as  far 
as  possible  all  that  you  take  from  it.  Other  expedients  may  be 
resorted  to  with  great  advantage,  and  in  some  instances  are 
absolutely  necessary  to  insure  a good  crop;  as  subsoiling,  green- 
manuring,  underdrainage,  mulching,  and  rotation  of  crops. 

Briefly  adverting  to  my  analysis,  I give  below  a succint  state- 
ment of  its 

RESULTS. 

First : observations  made  at  the  place  of  procuring  soil  speci- 
men. The  sample  which  I selected  for  analysis,  was  some  sub- 
soil near  the  propagating  house.*  I find  it  to  be  a hillside  soil 
of  adobe  character — surface  soil  one  foot  deep — subsoil  is  of 
light,  yellow  color,  and  has  the  appearance  of  containing  much 
clay;  natural  growth — oaks.  The  soil  is  derived  from  the  de- 
composition of  coarse  and  soft  clayey  sandstone,  together  with 
washings  from  the  hill. 

Second,  I give  in  a tabular  form  the  results  of  the  mechanical 
and  chemical  analyses. 


*0n  the  University  Grounds. 


12 


BULLETIN  OF  THE 


Table  of  Mechanical  Analysis. 

GRAMMES. 

Amount  taken  for  Analysis 19.34 

PER  CENT. 

(Hygroscopic  Moisture 9.07) 

Clay 24.7 

Sediment  of  <0.25  m.  m.,  i.  e.  finest  silt .24.5 

££  .25  m.  m. — 2 m.m.,  i.  e.  remaining  silt.  11.0 

££  4 m.  m.  i.  e.  Dust  Sand 6.3 

t£  8 ££  <c  Finest  sand 5.3 

££  16  “ ££  Fine  sand. . 6.2 

££  24  ££  ££  Medium  sand 6.0 

££  >24  ££  ££  Coarse  and  medium  sand.  . 8.9 

Table  of  Chemical  Analysis. 

GRAMMES- 

Amount  taken  for  Analysis 2.467 

PER  CENT.. 

Insoluble  Residue 80.79 

(Si02  soluble 5.01) 

K20 65 

Na20 05 

CaO 35 

]#gO 50 

Mn304  22 

Fe203 5.50 

A1203  (By  diff.) 6.43 

P205 09 

S03 .10 

Water  and  volatile  matter 5.32 


My  analysis  may  simply  be  regarded  as  a preliminary  one. 
The  first  analysis  is  generally  considered  as  one  giving  valuable 
suggestions  only,  to  be  made  use  of  in  a second  analysis  of  the 
soil,  and  also  indicating  much  real  information  as  to  the  soil's 
chemical  and  physical  composition. 

I could  not  have  hoped  to  have  obtained  more  than  ap- 
proximate results;  since  in  the  mechanical  analysis,  the 
elutriator  which  I used  is  the  one  designed  for  coarse  sed- 
iments only,  and  in  consequence  of  its  conical  form,  it  ad- 
mits of  the  formation  of  return  currents,  which  cause  the 
single  grains  of  sediment  to  aggregate  into  heavy  masses. 

And  in  the  chemical  analysis,  the  chemicals  which  I used 

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UNIVERSITY  OF  CALIFORNIA. 


13 


were  not  as  pure  as  they  should  have  been,  nor  was  I as  suc- 
cessful in  the  use  of  them  as  I might  have  desired.  However, 
uniting  the  observations  made  at  the  locality  where  I obtained 
my  specimen,  with  the  results  of  the  physical  and  chemical  anal- 
yses, one  may  arrive  at  satisfactory  conclusions  for  an  approxi- 
mate analysis. 

Making  use  of  my  results,  then,  as  the  basis  of  my  observa- 
tions in  reference  to  this  soil,  I should  say,  from  the  chemical 
analysis,  that  the  soil  contains,  as  most  clay  soils  do,  a large 
amount  of  K20,  but  a small  amount  of  lime;  which  indicates 
that  much  of  the  K is  in  an  unavailable  form.  Hence  in  all  pro- 
bability the  productiveness  would  be  greatly  increased  by  the 
application  of  lime. 

The  consideration  of  the  mechanical  analysis  shows,  more- 
over that  even  a small  addition  of  lime  would  be  of  advantage 
in  improving  the  tillable  qualities  of  this  soil,  since  the  clay 
percentage  is  not  very  large.  Hence  in  this  double  point  of 
view,  the  application  of  lime  is  indicated  as  likely  to  be  of  espec- 
ial advantage  to  this  soil. 


We  may  confidently  say  that  by  properly  combining  th^exa- 
mination  of  the  physical  and  chemical  properties  of  soil  and 
clays  we  shall  be  able  to  fulfill  in  great  measure  the  high  expecta- 
tions entertained  in  the  early  days  of  agricultural  chemistry. 

As  furnishing  knowledge  of  the  soil,  soil  analysis  is  of  prime 
importance  and  is  at  the  foundation  of  all  agricultural  opera- 
tions. One  cannot  have  a satisfactory  or  sufficient  knowledge 
of  his  soil  until  he  has  had  it  carefully  analyzed.  Uniting  the 
information  so  derived  with  that  obtained  by  his  own  or  other’s 
observations, experiments,  and  experiences, the  farmer  can  then, 
and  only  then,  intelligently  cultivate  his  soil. 


151 


